Cut pork into thin slices and flatten with the side of a meat cleaver to 2 inch diameter.
Braise the pork in butter until done, very slowly at first, then increase heat until centre is pink.
To make the sauce, melt 4 Tbsp butter in another pan.
Add onions, garlic and celery tops.
Cook until onions are soft.
Blend in flour.
Add chicken broth, basil, nutmeg, beef extract and wine.
Cook until thick.
Add cream and sour cream over very low heat and stir until blended.
To serve, spoon sauce over cooked pork.
serve warm.